Adjusting screw for firearms



VOct- 7, 1952 c. H. CLEVELAND 2,612,820

ADJUSTING SCREW FOR FIREARMS v Filed March 8, 1950 .m W M al@ PatentedOct. 7, 1952 ADJUSTTNG SCREW Foa EIREARMS Charles H. Cleveland,Springfield, Mass., assigner to the United States of America asrepresented by the Secretary of War Application March 8, 1950, SerialNo. 148,441

(Granted under the act of March 3, 1883, as amended April 3i), 1928; 3700. G. 757) 3 Claims.

The invention described herein may be manuiactured and used by or forthe Government for governmental purposes without the payment of anyroyalty thereon.

This invention relates to means for varying the tension of a firearmbuier spring and iS more particularly directed to an improved adjustingscrew therefor.

Automatic firearms are commonly provided with some means for cushioningthe shock of a recoiling bolt immediately prior to the counterrecoilmovement thereof. For example, the caliber .50 Browning machine `gunutilizes a set of washer-like Springs seated in a tubular housing whichextends rearwardly from the back plate. These springs are arranged to beinitially compressed between a buffer member mounted in the front endand an adjusting screw threaded into the rear end of the tubularhousing. Thus,

adjustment of the screw serves to control the extent of the bufferaction provided on the recoiling bolt in the gun.

When the adjusting Screw is assembled into the tubular spring housing tothe depth desired, the reduced diameter end of a spring biased plungerprojects from the side of the screw into either one of a pair ofoppositely disposed slots provided in the Walls of the housing andthereby serves to lock the screw to the housing. Consequently, it isnecessary to depress the plunger by means of a suitable tool or driftinserted through one of the slots before the screw can be rotated forfurther adjustment or disassembly purposes. When 180" rotation thereofhas been made, the reduced end of the plunger ywill automaticallyproject into the other of the housing slots. It can thus be readily seenthat the aforesaid manipulation of the plunger depressing tool must berepeated at every 180 turn of the adjusting screw. Obviously suchprocedure is tedious and time consuming.

It is therefore an object of this invention to provide improved meansfor locking and unlocking the adjusting member of a firearm buffermechanism.

It is a particular object of the present invention to provide aself-locking and unlocking adjusting screw for the buffer assembly of acaliber .50 Browning machine gun.

The specilc nature of the invention aswell as other objects andadvantages thereof will clearly appear from a description of a preferredembodiment as shown in the accompanying drawings, in which:

showing the latch in its depressed position; and

Fig. 7 is a cross-sectional view taken along the line 'l-l in Fig. 6.

Referring now to the drawing there is illustrated in Figs. 2 and 3 aback plate member particularly designed for use with Browning typemachine guns. Such back plate essentially comprises a substantiallyrectangular portion 5 arranged to serve as the rear end wall of thereceiver (not shown) and an integral rearwardly extending tubularhousing 6. A buier spring l consisting of Va set of slightly concavewasherlike members is so disposed within housing 6 that the concave andconvex faces thereof alternate in succession. Spring 'I Seats lagainsta.

cylindrical buffer member 9 slidably but snugly disposed in a centrallylocated counterbored opening Hi extending through rectangular portion 5.Member 9 is provided with an annular beveled surface ll arranged to matewith a similarly beveled shoulder l2 formed in opening lil so that thefront end of member 9 protrudes slightly beyond the back platerectangular portion 5 for contact with a recoiling bolt (not shown). Theinner periphery of the rear end portion of housing 6 is threaded asshown at I3 for receiving a disk-like -adjusting screw I4.

A longitudinal axial hole I6 is provided through screw I4 and acylindrical recess I5 is formed in the rear face thereof on either sideof hole I6. Recesses i5 are in alignment with the ver-` tical axis ofhole I6. A transverse counterbored hole Il forms a shoulder I8 and alsoextends through screw I4 so as to intersect axial hole i6 substantiallyat right angles.

A plunger i9 is slidably mounted in counterbored hole I'i and isarranged to be biased by a coil spring 20 interposed between shoulder I8and one end of plunger IIJ. The other end thereof is of reduced diameteras best shown at 2| in Fig. 4 and is normally arranged to extend intoeither of a pair of longitudinal slots 22 diametriis a cross-sectionalview taken along cally disposed on opposite sides of -housing 6. Asection oi plunger I9 is cut away as illustrated at 23 and one side wallof such cut-out section is provided with a ramp surface 24.

A latch225` is Pslidably.- disposedy in r` axial hole` I6 ofadjustingfrzscrewf I4fso as to extend through.`

and beyond plunger cut-out section 23. Such latch comprises acylindrical head 26 and an in-4 tegral body 21 slabbed oir as shown at28. Body 21 terminates in a hook portion"29"and^is also provided with acam surface-30extendingfupf--- wardly therefrom.

When properly assembled, thel indented portion of body 21 between hook29 andcam surface..

30 receives plunger ramp surface' 24 under the' bias of spring 20. Inthis position, thereduced` end 2| of plunger I9 extends into one ofhousing slots 22 thereby preventingany,furtherrotation' Y of adjustingscrew I4 which has` been threaded" intohousing to the extent determinedby the amount -of tension -d'e'siredi--inbui'er'lspr-ing -1..-

However, when' latch 25 is depressed by means plungerl I Ill is cammed"-to-y the-position show nf-in` Fig.v 7 bycontact-fofvlatchcamfsurface-Billon rampe-surface 24; Consequentlyplunger'end- -2I is withdrawn out of slot 22`-a-llowing rotation 'of ivscrew I4? Tool-f3`l isfof course; provided with a central pin 32arranged-todepress latcht.25when' seated-*in-y recesses- I5. Thus whentool-Slis rotated, adjusting screw I4'-fwill'be rotatedv in the samedirection-to"advancecor retract in housing Uponfremoval of tool 31,spring 2U will bias plunger'ramp surface'l24--against latch cam sur face30 thereby returning latch 25y to a pre-depressed-position. If eitherone of slots-L22 is a1ig'nedi-with-counterbored `hole I1 in screw- I4,-

plunger ^I9- will assume `the locked position. shown However,` ifv`suchA` alignment: is: not

infrfig.- 3. presentwhen rotation of screw I4 is halted, thevibration'causedfbyfringof the gun will automatically rotate screwf I4!until the aforesaid a'lignmentlis attained.

` Thus-there isf-here provided simple yetpositiveime'ans for locking'-and unlockingl the-.adjustingscrew-inthelbulerf mechanism for-a Browning -machine gun. The structure-y herev disclosedentirelyeliminatesathevprior 'art' necessity for:

halting @the-rotation: of the` adjusting screw after` 'each'. 180. turnvin order.. to move. the; tool to. the..-

n'ewip'ositi'on reachedby..'therplunger. It is ob# vi'ous.: that.. thelatch :of 1 this. invention.:v will hold thenplungerendzout `ofxtheslots in the buffer.`

housingas long as` it isA depressedbyumeansof theI which the-toolistofbe put:

-Ifclaimr y 1'. Inabnermechanism. for anrearm. back.

plate ,having a-rearwardly extending tubular* buffer` housing-thevcombination of,. avv buierV member-,longitudinally mounted in the backplate; so sasl-"t0 protrude slightly,- therefrom,` an adj ust'VY ingscrew threadably secured into the rear end of the buier housing, a buierspring interposed between said buffer member and said adjusting screwwhereby rotative movement of the latter varies the .amount ofresistance-of7 the lrformer to impact,'.thei^housing havingaa pai'roflongitudinally extending slots formed on opposite sides thereof, aspring biased plunger transversely mounted in said adjusting screw andnormally arranged'toprotrude therefrom into one of said slotsin said;`housing for preventing rotative movementfof'sai'd screw, a latchslidably carried inlsaidzs'crew forlimiting the slot-engaging movementof. said plunger, and cam means on said latch for actuating said plungerout of said housingjslots when `said latch is depressed into saidadjusting screw.

2".` Means for#V unlocking a buffer adjusting screw in' arearm bufferhousing, comprising, a plunger transversely disposed in the adjustingscrew; spring means-normally y urging oneend'of saidjlplungerintoengagement with tl'ie'bi'iierf4 housin'gftoprevent rotationl offthefad'justir'ig screw, said plunger havingaf-substantially-'recetangula-r cut-outsect-ion and a ramp 'por-tionononesi'de wall thereof, a latch longitudinally=dis-'-L posed' kvintheadjusting screw for slidable-move-- ment, said latchcomprising?acylindricalhead1 anda `slabbed body terminating in a-hookuportion,l said plunger rampV portion arrangedfto'be engaged bysaid latch' hookf portion `forl prevent-- ing'movement'of said latchoutof the'adjustingfscrew; and a cam surface on said 'latch' bodyfextending upwardly fromsaidfhookl portion"V and arranged to contacttheface vof said rarnp4 portion` in said: plungerA wherebyA movement Aofsaid latch downwardly linto the adjustingscrew cams--saidplunger-outwofv engagement withtlre-f i f 3.V In a rearm having afbackplate-andrabuffer: housing v integral therewith,y thecombina-- tionof, a buffer member slidably-protruding` throughv` the.' back plate,` anadjusting: screw Y threadably secured in' the b'uierhousing'zzresilient.`

means. interposedv between'sai'd buffer" member? andsaid. adjusting fscrew and. arranged. to" resisti rearward movement of Ysaid; buffermembenz; spring-biased` plunger: transverselyVV mounted.; 1n:- said`Vadjusting Vscrew .'andnnormally VengagedY in: the' housing; thereby`preventing;` rotation:v ofl :said i l adjusting screw, said plunger..havingga ;,ramp i portion onone side-thereon, a latch` longitudinally:mounted. in saidadjusting. screw vfor slidable. movement therein,y andcam means onsaid latch,` cooperatingl with said rampportionfor=retract--l ingA said ,plunger outof the housing thereby'permittingmotation-of said adjusting screw. .Y y

CHARLES/H.V CLEVELAND..

, v REFERENCES CITED The following references. are ot recorvslH-in` .thele o1?` this-patent:

- UNITED: sTATEsPATENTs...

l\hinob"er Name Date-j 1,519,458 Kauch et al. Dec 16,'1924"n

